To what volume should 5.0 g of #KCl# be diluted in order to prepare 0.25 M solution?

1 Answer
Walker P
Mar 5, 2016

0.27 L

Explanation:

We are looking for volume and are given a mass and a molarity.

Note:

#M=(mol_(solute))/(Liters_(solution))#

Rearranging this equation to solve for volume:

#L_(solution)=(mol_(solute))/M#

We have M, but we need #mol_(solute)#. To get this, we use the molecular weight of KCl, which is:

#74.55 g_(KCl)/(mol_(KCl))#

To get the moles of KCl:

#5.0 g_(KCl)*(1 mol_(KCl))/(74.55g_(KCl))=0.067mol_(KCl)#

Finally, plug back into the equation for #Liters_(solution)#:
#L_(solution)=(mol_(solute))/M#
#L_(solution)=(0.067mol_(KCl))/(0.25*(mol_(KCl))/(L_(solution))#
#L_(solution)=0.27 L#

Note: This is the total solution volume, not the volume of solvent. Total volume of solute + solvent is the solution volume.

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